The upcoming model experiments of the phase 6 of the Coupled Model Intercomparison Project (CMIP6) are currently organized in 21 Model Intercomparison Projects (MIPs). Compared to other MIPs, the experiments of HighResMIP are both computationally and I/O intensive. The model experiments of this MIP might consume ~100 M CPU hours and ~1 PB of data storage, thus computational scalability of the coupled system and planning for data management is extremely essential.
The scalability of the Norwegian Earth System Model (NorESM - a model based on the CESM framework) is studied for quarter degree atmosphere component and quarter degree ocean component. With the same resolution, we plan to participate in CMIP6 HighResMIP with tier-1 and tier-2 experiments. Both Norwegian HPC infrastructure and PRACE systems were used for scalability experiments.
The scalability of individual components (atmosphere, ocean, land and ice) and coupled system scalability are examined. Finite volume and spectral element horizontal discretization of the atmosphere component are compared in standalone configurations. The effect of I/O (with varying data size, serial I/O and parallel I/O ) on speed-up and scalability of the model is also examined as HighResMIP's data requirements are considerable.